1) Original Birth Certificate issued by Muncipal Corporation or Equivalent Authority.
2) Proof of residential address (passport/Lease Deed/ latest paid Electricity Bill/ MTNL Bill/Electoral Card. Incase of rental accommodation, rent agreement and an affidavit on stamp paper to be submitted)
3) Self Certification of parents with regard to Girl Child or first born child. An affidavit can also be asked in some schools.
4) Affidavit in case of Single Parents.
5) Proof/Certificates of Track record of parents, in case it is mentioned by the school or points are being allocated for that.
6) In case of sibling applicants, the school Identity Card of sibling studying the school.
7) In case of applicants with special needs- Certificate of disability issued by the competent authority.
For transfer cases – Proof of Transfer to Delhi.-Certificate/ Transfer Order and joining report stating date of transfer and joining.
9) Passport Size Photographs of the Child as well as the parents.
10) Immunization Chart of the Child.
11) Alumni Cases – Proof of Alumni (Identity Card)
12) Baptism certificate and a letter from the Parish Priest (for Catholics) – Was asked by Don Bosco School
13) For EWS – Economically Weaker Section Category – Income certificate issued by the S.D.M. of the area or any other Revenue Officer not below the rank of the Tehsildar / Food & Supplies Officer, Deptt. of NCT of Delhi and Letter from the parents of the candidate stating the parental income.
14) Single Parent – Affidavit certifying the same.

Source: http://www.indianexpress.com/news/nursery-admissions-adopted-firstborn-children-to-get-extra-points/892478/